Incandescible cathode discharge tube having a gaseous filling



A. KUNTKE June 12, 1934.

INCANDESCIBLE CATHODE DISCHARGE TUBE HAVING A GASEOUS'FILLING OriginalFiled May 15, 1933 //Vl f/VTOR ALFRED KUNTKE Patented June 12, 1934UNITED STATES PATENT OFFICE INCANDESCIBLE C A T H O D E DISCHARGE TUBEHAVING A GASEOUS FILLING Alfred Kuntke, Eindhoven, Netherlands,assignor, by mesne assignments, to N. V. Philips Gloeilampenfabrieken,Eindhoven, Netherlands,

a Dutch comnany 6 Claims. (01. 250-215) The present invention relates togas-filled in candescible cathode discharge tubes and more particularlyto such tubes as described and claimed in the copending application ofJ. G. W. Mulder and myself, Serial Number 671,240, filed May 15, 1933,from which application the subjectmatter of this application has beentaken.

These tubes have a plurality of metal bodies disposed between theiranode and cathode, which 0 bodies surround the discharge path. Thesemetal bodies have the effect that the voltage across the discharge pathis sub-divided. In order that the bodies have always the rightpotential, they may be interconnected by impedances, for example,

condensers which are thereby connected in series across the terminals ofthe tube and maintain the proper voltage distribution throughout thepath of the discharge.

The conductive bodies have small mutual distances and the diameter ofthe glass wall surrounding the spaces between the bodies areconsiderably larger than the path of the discharge confined by theconductive bodies, so that electric charges on the glass wall do notaffect the course of the discharge.

One object of the present invention is to entirely eliminate anyinfluence of wall charges on the discharge path.

A further object of my present invention is to provide for a betterdistribution of the voltage.

A still further object is to avoid the use of external impedances forthe division or the voltage.

My invention comprises using metal bodies having portions that projectwithin or telescope with portions" of adjoining bodies, thus shieldingthe discharge path from the wall ofthe tube. The distance between theoverlapping portions preferably does not exceed a few millimeters.

These overlapping portions form together a condenser and consequentlythere are a number of condensers at least one less than the number ofconductive bodies connected across the discharge path. These condensersact as the impedances above referred to. The impedances externallymounted may therefor be smaller or if the capacity of the internalcondensers is large enough may be dispensed with altogether. In order toenhance the capacity between the adjoining bodies the overlapping may bebilateral.

Preferably the innermost portion of the conductive bodies is turnedtowards the anode. This appears to result in a somewhat greater backignition voltage.

In a very simple form the bodies have the shape of open ended truncatedcones, which partly overlapeach other and have their wider edgessupported by the wall of the tube.

My invention will be more clearly described by reference to theaccompanying drawing representing by way of example three embodimentsthereof. Each of the figures is a section through a portion of adischarge tube showing a number of conductive bodies surrounding thepath of the discharge.

In Fig. 1 the bodies overlap each other at one side only.

In Fig. 2 the overlapping is made bilateral.

In Fig. 3 the bodies have a truncated conical shape.

A wall consisting of metal sleeves 1 and glass portions 2 sealed to theedges of the sleeves forms a tubular portion of the discharge tube inFigs. 1 and 2. At one endof the this portion an incandescible cathodes 3is arranged and at the other end an anode 4.-

The drawing represents only part of the tubular portion. The ends of thetube and the electrodes may be shaped as more fully described in theaforesaid application. The sleeves 1 form portions of metal bodiesconsisting in the modification shown in Fig. 1 of a narrower tubularportion 5 and a wider tubular portion 6, the latter being turned.towards the cathode 3. The portions5 are surrounded by the portions 6,thus the discharge path confined by the inner surface of the portions 5is entirely shielded against the portions 2 of the tube wall. Electriccharges on these glass portions cannot influence the dis chargephenomenon since no electric line of force starting from these portionscan penetrate into the discharge path. The adjoining portions 5 and 6have a considerable surface and a very small mutual distance.Consequently they present a condenser of considerable capacity and asone metal body has a surrounded portion adjoining the preceding body anda surrounding portion adjoining the next body, all these condensers areconnected in series and take each an equal portion of the voltage. I

This voltage dividing effect is enhanced by making the usual distancesof the metal bodies as small as possible (a few millimeters or evenless) and by enlarging the surfaces of the condenser plates. Such anenlargement is shown in Fig. 2 in which the bodies have one portionconsisting of a double cylinder (7, 8) between which extends the otherportion (9) of the next body (as considered from the side of thecathode). The surface of each condenser is thereby made nearly twice aslarge as in the embodiment shown in F18. 1.

In Fig. 3 the tubular bodies 10 have the shape of open ended truncatedcones, which partly overlap each other and which thereby provide for thedesired capacity effect, and at the same time the smaller bases beingturned towards the anode, provide for a reduction of the discharge pathdiameter in this direction which has proved to be more favourable withrespect to the danger of back ignition than the reverse arrangement.

The edges 12 of the bodies 10 are flared outwards and sealed to theglass wall 11, thus forming partitions that divide the tube in a numberof sections. The capacity between the metal bodies widely depends on thedistance in axial direction; varying this distance causes both theadjoining surfaces and the mutual distance to be varied. Therefore thismode of realization is less reliable than the first ones, also becauseshielding oif the discharge path is not so completely effected, but itis less expensive to make.

What I claim is:

' 1. A discharge tube for high voltages comprising a gaseous filling, anincandescible cathode and an anode disposed at the two ends of the tube,and a plurality of tubular metal bodies between said cathode and anodeand surrounding the discharge path, portions of said bodies projectingwithin portions of adjoining bodies.

2. A discharge tube-for high voltages comprising a gaseous filling, anincandescible cathode and an anode disposed at the two ends of the Itube, and a plurality of substantially identical tubular metal bodiessurrounding the discharge path, portions of said bodies telescoping withadjoining bodies, thedistance between the opposing ends and theoverlapping portions being of the order of a few millimeters.

3. A discharge tube for high voltages comprising a gaseous filling, anincandescible cathode and an anode disposed at the two ends of the tube,and a discharge path between same, a piurality of conducting cylindricalbodies surrounding the discharge path, said bodies having portionsbilaterally overlapping adjoining bodies, the distance between theopposing ends and overlapping portions of adjoining bodies being of theorder of a few millimeters.

4. An electric discharge tube for high voltages comprising, a vitreousenvelope, a gaseous filling, an incandescible cathode and an anode, saidcathode and anode being disposed at the two ends of the tube, and adischarge path between same, a. plurality of open-ended truncatedconical members disposed in said tube and surrounding the dischargepath, and having their smaller bases turned towards the anode, saidmembers protruding into each other.

5. A discharge tube for high voltages a vitreous envelope, having acylindrical portion, a plurality of metal partitions in said cylindricalportion, said partitions having the shape of open ended truncated cones,disposed with their smaller 100 bases turned in the same direction andhaving at their opposing bases a flared out rim sealed into thecylindrical wall portion.

6. An electric discharge tube for high voltages comprising a cylindricalenvelope having insulating portions, an incandescible cathode, an anodeand a gaseous filling therein, a discharge path between said cathode andanode, and hollow conducting bodies disposed between said cathode andanode and surrounding the discharge path, said conducting bodies beingconnected to the insulating portions of said envelope, said hollowconducting bodies telescoping with each other.

